m = 2000003

def MyHash(k,i):
    return (k%m+i*(1+(k%m)))%m

def main():
    n = input()
    T = ['']*2000003
    O = []
    for i in range(n):
        c, k = raw_input().split()
        i = 0
        if c == 'insert':
            k_hashed = hash(k)
            while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
        else:
            O.append(search(T,k))

    for item in O:
        print item

    return 0


def search(T,k):
    k_hashed = hash(k)
    i = 0
    while True:
        j = MyHash(k_hashed,i)
        if T[j] == k:
            o = 'yes'
            break
        elif T[j] == '':
            o = 'no'
            break
        else:
            i += 1

    return o


if __name__ == "__main__":
    main() m = 2000003 m 2000003 def MyHash(k,i):
    return (k%m+i*(1+(k%m)))%m MyHash return (k%m+i*(1+(k%m)))%m (k%m+i*(1+(k%m)))%m k%m+i*(1+(k%m)) k%m k m i*(1+(k%m)) i 1+(k%m) 1 k%m k m m k k i i def main():
    n = input()
    T = ['']*2000003
    O = []
    for i in range(n):
        c, k = raw_input().split()
        i = 0
        if c == 'insert':
            k_hashed = hash(k)
            while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
        else:
            O.append(search(T,k))

    for item in O:
        print item

    return 0 main n = input() n input() input T = ['']*2000003 T ['']*2000003 [''] '' 2000003 O = [] O [] for i in range(n):
        c, k = raw_input().split()
        i = 0
        if c == 'insert':
            k_hashed = hash(k)
            while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
        else:
            O.append(search(T,k))

     i range(n) range n c, k = raw_input().split() c raw_input().split() ().split () raw_input split k i = 0 i 0 if c == 'insert':
            k_hashed = hash(k)
            while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
        else:
            O.append(search(T,k))

     c == 'insert' c 'insert' k_hashed = hash(k) k_hashed hash(k) hash k while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
         True j = MyHash(k_hashed,i) j MyHash(k_hashed,i) MyHash k_hashed i if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
         T[j] == '' T[j] T j '' T[j] = k T[j] T j k break i += 1 i 1 O.append(search(T,k)) O.append O append search(T,k) search T k for item in O:
        print item

     item O print return 0 0 def search(T,k):
    k_hashed = hash(k)
    i = 0
    while True:
        j = MyHash(k_hashed,i)
        if T[j] == k:
            o = 'yes'
            break
        elif T[j] == '':
            o = 'no'
            break
        else:
            i += 1

    return o search k_hashed = hash(k) k_hashed hash(k) hash k i = 0 i 0 while True:
        j = MyHash(k_hashed,i)
        if T[j] == k:
            o = 'yes'
            break
        elif T[j] == '':
            o = 'no'
            break
        else:
            i += 1

     True j = MyHash(k_hashed,i) j MyHash(k_hashed,i) MyHash k_hashed i if T[j] == k:
            o = 'yes'
            break
        elif T[j] == '':
            o = 'no'
            break
        else:
            i += 1

     T[j] == k T[j] T j k o = 'yes' o 'yes' break elif T[j] == '':
            o = 'no'
            break
         T[j] == '' T[j] T j '' o = 'no' o 'no' break i += 1 i 1 return o o T T k k if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def search(T,k):
    k_hashed = hash(k)
    i = 0
    while True:
        j = MyHash(k_hashed,i)
        if T[j] == k:
            o = 'yes'
            break
        elif T[j] == '':
            o = 'no'
            break
        else:
            i += 1

    return o def search(T,k):
    k_hashed = hash(k)
    i = 0
    while True:
        j = MyHash(k_hashed,i)
        if T[j] == k:
            o = 'yes'
            break
        elif T[j] == '':
            o = 'no'
            break
        else:
            i += 1

    return o search def main():
    n = input()
    T = ['']*2000003
    O = []
    for i in range(n):
        c, k = raw_input().split()
        i = 0
        if c == 'insert':
            k_hashed = hash(k)
            while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
        else:
            O.append(search(T,k))

    for item in O:
        print item

    return 0 def main():
    n = input()
    T = ['']*2000003
    O = []
    for i in range(n):
        c, k = raw_input().split()
        i = 0
        if c == 'insert':
            k_hashed = hash(k)
            while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
        else:
            O.append(search(T,k))

    for item in O:
        print item

    return 0 main def MyHash(k,i):
    return (k%m+i*(1+(k%m)))%m def MyHash(k,i):
    return (k%m+i*(1+(k%m)))%m MyHash m = 2000003 2000003 m
m = 2000003

def MyHash(k,i):
    return (k%m+i*(1+(k%m)))%m

def main():
    n = input()
    T = ['']*2000003
    O = []
    for i in range(n):
        c, k = raw_input().split()
        i = 0
        if c == 'insert':
            k_hashed = hash(k)
            while True:
                j = MyHash(k_hashed,i)
                if T[j] == '':
                    T[j] = k
                    break
                else:
                    i += 1
        else:
            O.append(search(T,k))

    for item in O:
        print item

    return 0


def search(T,k):
    k_hashed = hash(k)
    i = 0
    while True:
        j = MyHash(k_hashed,i)
        if T[j] == k:
            o = 'yes'
            break
        elif T[j] == '':
            o = 'no'
            break
        else:
            i += 1

    return o


if __name__ == "__main__":
    main()